Gate valves are a type of valve used to control the flow of liquids, gases, vapors and slurries in piping systems. They operate by opening or closing to allow or stop flow. Gate valves are linear motion valves consisting of a movable gate that slides down to shut off flow or lifts up to allow flow. They are primarily used for on/off applications rather than for throttling or regulating flow.
Gate valves have been around for over a century and are one of the most common types of valves found in industrial plants, commercial buildings and residential plumbing systems. They come in a range of sizes, pressure ratings and body materials for diverse applications. As with all technologies, gate valves have both advantages and disadvantages compared to other valve types. Analyzing the pros and cons of gate valves can help end users select the most suitable valves for their specific needs.
What Are The Advantages Of Gate Valves?
Gate valves offer a number of benefits that make them a popular choice in many flow control situations. Some of the main advantages include:
- Low Pressure Drop – The flow path through an open gate valve is straight through, causing very little pressure drop or restriction. This makes gate valves suitable for applications where minimal head loss through the valve is desired.
- Good Sealing Ability – Gate valves provide effective shutoff with tight sealing when closed, preventing leakage even at high pressures. The gate slides into seat rings, creating a robust seal. This makes gate valves a good option when zero leakage is critical.
- Low Torque Operation – Opening or closing a gate valve requires relatively low torque compared to other valve types. Small handwheels are often sufficient for manual operation. This makes gate valves easier to operate without large actuators.
- Bidirectional Flow – Gate valves allow flow in either direction and are often used where the flow can reverse. Check valves are not suitable for bidirectional applications.
- Reliable And Durable – Gate valves are generally very reliable and durable when properly selected for the service conditions. Their simplicity of operation with few moving parts contributes to long service life.
- Relatively Low Cost – Simple gate valve designs allow economical manufacturing. Gate valve pricing is competitive, providing a cost-effective flow control solution.
- Easy Maintenance – The straightforward design of gate valves enables easy disassembly for maintenance. Internal components can be accessed by removing the bonnet. No special tools are required.
- Familiar Technology – Gate valves have been used for generations, so operating companies and personnel are knowledgeable about their operation, strengths, and limitations. Their prevalent use makes gate valves easy to source and replace if needed.
What Are The Disadvantages Of Gate Valves?
While gate valves have numerous advantages, they also come with limitations that are important to recognize:
- Not For Throttling Service – Gate valves are unsuitable for continuously regulating or throttling flow. Attempting to use them for throttling can damage the gate or seats.
- Limited Low-Pressure Use – Gate valves are not recommended for vacuum service below around 10 psi. Performance declines under very low pressures. Click here to learn how to choose the right vacuum valve.
- Poor Cavitation Performance – The relatively large clearances can induce cavitation damage when used on liquids with high-pressure drops.
- Slow Operation Time – Opening or closing a gate valve takes more time compared to 1/4 turn ball or plug valves. This may be problematic for cycling services.
- Not Ideal For Frequent Operation – Gate valves are best suited for infrequent, fully open or fully closed service rather than high cycling operation.
- Risk Of Slam Closure – Gate valves can unexpectedly slam shut if the control switch or air supply fails. Sudden closure can be hazardous.
- Potential To Freeze In Cold Weather – Gate valves used outdoors in cold climates risk freezing up if condensation occurs past the gate area.
- Potential For Binding – Build-up, improperly installed packing or misalignment can cause the gate to stick or bind rather than slide smoothly.
These limitations mean gate valves may not be the optimal choice for all applications. Understanding where gate valves excel and where they fall short is key to the right selection.